Determinants of insulin secretion and sensitivity in bangladeshi type 2 diabetic subjects

Background: The relative contribution of insulin secretion and sensitivity in the development of type 2 diabetes mellitus (T2DM) vary from population to population due to the heterogeneous nature of the disease. The study was undertaken to evaluate the insulin secretory capacity and sensitivity in a Bangladeshi type 2 diabetic population and to explore the association of some of the anthropometric (BMI, WHR, MBP) and biochemical factors (glucose, lipids, HbA(1c)) known to modulate B-cell function and insulin action. Methods: Ninety three T2DM and 70 age-matched control subjects were studied for their fasting glucose, lipids, HbA(1c) (by HPLC) and C-peptide (by ELISA). Insulin secretion (HOMA B) and insulin sensitivity (HOMA S) were calculated by homeostasis model assessment (HOMA). Results: Both insulin secretion and sensitivity were significantly reduced in diabetic as compared to control subjects (HOMA B%, geometric M +/- SD, 34.67 +/- 1.73 vs 104.71 +/- 1.34, p < 0.001; HOMA S%, 67.60 +/- 1.69 vs 85.11 +/- 1.54, p < 0.01). However, the discriminant function coefficient for HOMA B (1.142) was about 1.5 times higher than that for HOMA S (0.731). In T2DM, HOMA B had positive correlation with BMI (r = 0.362, p < 0.001) and inverse correlation with plasma glucose (r = - 0.701, p < 0.001) and HbA1c (r = - 0.612, p < 0.001). HOMA S was inversely correlated to BMI (r = - 0.274, p < 0.01), WHR (r = - 0.252, p < 0.05), plasma total cholesterol (r = - 0.240, p < 0.05) and triglycerides (r = 0.301, p < 0.01). Conclusions: Both insulin secretory dysfunction and insulin resistance are present in Bangladeshi T2DM subjects, but B-cell dysfunction seems to be the predominant defect. BMI, plasma glucose and insulin are the major determinants of insulin secretory capacity; and generalized as well as central obesity, plasma glucose, total cholesterol, triglycerides and insulin are among the major determinants of insulin sensitivity in this population.